Because of their increasing number of functions, modern controllers and control units, in particular those in a vehicle, for example engine controllers, transmission controllers, brake controllers, etc., need ever larger memory elements, in particular flash memories, for programs and data. These memories need to be programmed during manufacturing in the factory as well as undergo end-of-line programming by vehicle manufacturers and possibly also programming in repair shops in the field. The data to be programmed is usually transmitted to the controller via a serial interface that is otherwise used to transmit diagnostic information.
For this purpose, German Published Patent Application No. 43 32 499 describes a method for programming a memory in a control unit. According to this method, the data to be programmed is transmitted from an external electronic device, for example a personal computer, to the control unit. The serial interface used to transmit the data to be programmed is the existing serial diagnostic interface connecting the external electronic device to the control unit. The limited transmission rates achievable in this case, a maximum of 250 kbaud, result in ever longer transmission times, for example around 320 seconds for 8 MB.
It is an object of the present invention to shorten transmission times during programming while keeping costs low.
In recent years, the practice of networking controllers, sensors, and actuators using a communications system or bus system has increased dramatically in the manufacture of modern motor vehicles as well as the construction of machines, particularly in the machine-tool segment and in automation. It is therefore possible to utilize synergy effects by distributing functions among multiple controllers. This arrangement involves distributed systems or a controller network. Communication between different stations increasingly takes place via a bus or a bus system. Communications traffic on the bus system—access and receiving mechanisms—are controlled by a protocol.
A protocol that has been widely accepted in automotive applications is CAN (controller area network). It is an event-controlled protocol, i.e., protocol activities such as transmitting messages are initiated by events originating outside the communications system. Clear access to the communications system, i.e., bus system, is triggered by priority-based bit arbitration. To do this, each message must be assigned a clear priority. The CAN protocol is extremely flexible in that it allows additional nodes and messages to be added without problems.